The team at MIT created several types of robots, including a fin-like flapping machine, a bot that makes kicking motions, and a soft, hand-shaped claw with flexible arms.

Because the robots are both powered by, and made almost entirely of, water researchers say they can be virtually invisible. They found that when they placed the devices into water, they appeared almost entirely camouflaged.

Scientists released a video of the bots performing a number of tasks, including gently and stealthily grabbing a live fish. The surprised fish seems to have had no idea the machine was close by until it was trapped in its clutches.

“[The robot] is almost transparent, very hard to see,” Xuanhe Zhao, who is heading the project at MIT says. “When you release the fish, it’s quite happy because [the robot] is soft and doesn’t damage the fish. Imagine a hard robotic hand would probably squash the fish.”

“We are actively collaborating with medical groups to translate this system into soft manipulators such as hydrogel ‘hands,’ which could potentially apply more gentle manipulations to tissues and organs in surgical operations.”

The team has developed ways to adhere the hydrogels to various surfaces such as glass, metal, ceramic, and rubber using strong bonds that resist peeling.

In experiments, they found the structures were able to withstand repeated use without rupturing or tearing.